Psychopathy seems to be a little bit more frequent than you could explain by samutatien a recombination. There's this concept in evolutionary biology of frequency dependent selection. If psychopaths are rare enough, then they might have more children than the average. As long as we're all fairly trusting, because only three % of the population are psycopat, we don't run into psychopaths that often.
In a few decades, a torrent of new evidence and ideas about human evolution has allowed scientists to piece together a more detailed understanding of what went on thousands and even millions of years ago. Lesley Newson and Peter Richerson, a husband-and-wife team based at the University of California, Davis, have spent years together and individually researching and collaborating with scholars from a wide range of disciplines to produce a deep history of humankind. In A Story of Us, they present this rich narrative and explain how the evolution of our genes relates to the evolution of our cultures.